Account for SimOnly in makeTopEntity (#2897)

Note that we still want to generate `PortName`s for zero-width
constructs, we just don't want them split out.

changelog/2025-03-04T15_40_21+01_00_account_for_simonly

@@ -0,0 +1 @@
+FIXED: `makeTopEntity` now accounts for `SimOnly` constructs. This can prevent warnings in situtations where the `SimOnly` type would contain types `makeTopEntity` cannot handle.

clash-prelude/src/Clash/Annotations/TH.hs

@@ -90,6 +90,7 @@ import           Data.Generics.Uniplate.Data    (rewrite)
 import           Clash.Annotations.TopEntity    ( PortName(..)
                                                 , TopEntity(..)
                                                 )
+import           Clash.Magic                    (SimOnly)
 import           Clash.NamedTypes               ((:::))
 import           Clash.Signal                   ( HiddenClockResetEnable
                                                 , HiddenClock, HiddenReset, HiddenEnable
@@ -225,6 +226,7 @@ datatypeNameToPorts name = do
   constructors <- tryReifyDatatype [] datatypeCons name
 
   names <- case constructors of
+    _ | name == ''SimOnly -> return $ Complete []
     []  -> return $ Complete []
     [x] -> portsFromTypes (constructorFields x)
     xs  -> handleNamesInSum xs
@@ -283,6 +285,8 @@ typeTreeToPorts (ConTF name) = do
 typeTreeToPorts f@(AppTF (a,a') (b,b')) = do
   -- Gather types applied to a head type
   case unapp (AppT a b) of
+    -- Skip SimOnly constructs - they're always zero bits
+    (ConT x : _) | x == ''SimOnly -> pure (Complete [])
     -- Return the inner type for signals
     (ConT x : _ : _ : []) | x == ''Clash.Signal.Signal -> b'
     (ConT x : _ : _ : _ : []) | x == ''Clash.Signal.Delayed.DSignal -> b'

clash-prelude/tests/Clash/Tests/TopEntityGeneration.hs

@@ -67,6 +67,12 @@ data HKD f = HKD
     , fd2 :: OrderedCF 'True f  ("fd2" ::: Bool)
     }
 
+data RecordWithSimOnlyField = RecordWithSimOnlyField
+  { simOnlyField1 :: "a" ::: SimOnly (Signal System ("foo" ::: Int))
+  , simOnlyField3 :: "b" ::: Signal System (SimOnly ("bar" ::: Int))
+  , someOtherField :: "c" ::: Signal System ("wobble" ::: Int)
+  }
+
 
 topEntity1 :: "in1" ::: Signal System Int
            -> "in2" ::: Signal System Bool
@@ -225,6 +231,36 @@ expectedTopEntity8 =
     ]
     (PortName "out")
 
+topEntity9 :: (HiddenClockResetEnable System)
+           => "pair" ::: SimOnly (Signal System (Pair Bool))
+           -> "pair" ::: Signal System (SimOnly (Pair Single))
+           -> "out" ::: Signal System Int
+topEntity9 = undefined
+makeTopEntity 'topEntity9
+
+expectedTopEntity9 :: TopEntity
+expectedTopEntity9 =
+ Synthesize "topEntity9"
+    [ PortProduct "" [PortName "clk", PortName "rst", PortName "en"]
+    , PortName "pair"
+    , PortName "pair"
+    ]
+    (PortName "out")
+
+topEntity10 :: (HiddenClockResetEnable System)
+           => "record" ::: Signal System RecordWithSimOnlyField
+           -> "out" ::: Signal System Int
+topEntity10 = undefined
+makeTopEntity 'topEntity10
+
+expectedTopEntity10 :: TopEntity
+expectedTopEntity10 =
+ Synthesize "topEntity10"
+    [ PortProduct "" [PortName "clk", PortName "rst", PortName "en"]
+    , PortProduct "record" [PortName "a",PortName "b",PortName "c_wobble"]
+    ]
+    (PortName "out")
+
 topEntityFailure1
   :: "int"     ::: Signal System Int
   -> "tuple"   ::: ("tup1" ::: Signal System (BitVector 7), "tup2" ::: Signal System (BitVector 9))
@@ -300,6 +336,12 @@ tests =
       , testCase "topEntity8" $
           $(unTypeQ $ maybeBuildTopEntity Nothing 'topEntity8)
           @?= Just expectedTopEntity8
+      , testCase "topEntity9" $
+          $(unTypeQ $ maybeBuildTopEntity Nothing 'topEntity9)
+          @?= Just expectedTopEntity9
+      , testCase "topEntity10" $
+          $(unTypeQ $ maybeBuildTopEntity Nothing 'topEntity10)
+          @?= Just expectedTopEntity10
       ]
     , testGroup "Expected failures"
       [ testCase "topEntityFailure1" $